The hot zone of most vacuum resistance furnaces consists of four major components: heaters and their associated components, insulation (or reflective screens), hot zone support components, and workpiece-carrying hearths. These parts often need to be replaced regularly due to the problems of the material or the time of use. When the graphite hot zone's accessories should be replaced? Here are some conditions:

1. For those whose life span has reached the replacement deadline, it is necessary to replace it in principle (or let an experienced person identify it and decide whether or not to continue using it). For those who have not arrive their life expectancy and are temporarily not in use, they should be sealed in plastic bags, packed in cartons, and the number of furnaces, number of furnaces, reasons for replacement, sources, and dates should be indicated and properly kept.

2, For partially damaged (such as three segment crucible broken one segment) but not up to the end of their life, they may be scraped or replaced (for a new three segment crucible with only a few heats determined by the supervisor of the workshop to decide whether to use it or not, for a usable and sufficient set of patchwork, Keep it in storage where it can be used but not needed for the time being. For sealed storage, it is recommended that it be used on a purified stove.

3. Every time the furnace is removed, the oxides in the hot field shall be cleaned and the silicon infiltration on the graphite pieces shall be cleaned. The guide tube and the insulation cover shall be wiped cleanly to avoid the accident of contamination of the raw materials by debris. Take graphite pieces, in addition to personal safety, but also be careful and light, pay attention to the safety of graphite parts.

4, strictly in accordance with operating procedures to heating-up, fusion, melt back, furnace shut down, etc., to protect the graphite pieces. After each furnace is removed, carefully clean the graphite fittings, carefully check the status of the seed crystals and various graphite hot field components, and make detailed records.

5. Check the graphite fittings for cracks, especially for graphite crucibles, graphite pallets, and graphite crucible rods. If cracks occur, immediately report to the workshop supervisor and make a replacement. Make judgments or report on the workshop where dip silicon is present. 

6. After the graphite fittings have reached the end of their useful life, the graphite fittings (graphite trays, crucible rods, graphite crucibles) and other components that may cause heavy losses during the overdue period will be dismantled and replaced with new ones. The replaced graphite fittings will be sealed for storage. The workshop, technical office and production office will conduct the examination after the review, and other accessories such as heaters, insulation cylinders, flow guide tubes, etc. shall be inspected carefully to see if there are any micro cracks and defects. In principle, these graphite parts can continue to be used without the above defects.

7. Make a detailed record of the accidents of graphite hot zone accessories. A detailed record of the problematic graphite fittings should be made and assigned to the designated place to prevent confusion.